This application relates to and incorporates herein by reference Japanese Patent Application No. 2000-382520 filed on Dec. 15, 2000.
1. Field of the Invention
The present invention relates to a sensor attachment structure, which is suitable for attaching a temperature sensor for detecting cooling air temperature in an evaporator for an air conditioning device.
2. Description of Related Art
In a sensor attachment structure shown in FIG. 4A, a lead wire 12 connecting a sensor 11 is extended along an extending bar 21 and pinched in a pinch portion 22 at a position proximate to the sensor 11. As shown in FIG. 4B, the pinch portion 22 has two wall plates 24 defining a clearance 26a therebetween, and each of the wall plates 24 is provided with a protrusion 25 at the tip end thereof, so that a clearance 26b defined between the protrusions 25 is narrower than the clearance 26a. 
As shown in FIG. 5, if a tensile force F is exerted to the lead wire 12 in an opposite direction to the sensor 11 when a sensor unit 10 attached to the bracket 20 is assembled to an air conditioning case 31 with a fixing portion 23, a tip side of the extending bar 21 of the bracket 20 is readily deflected. In this case, since a contact surface 22a that contacts the sensor 11 is inclined in a direction to the tensile force F, a component force F1 of the tensile force F is exerted along the contact surface 22a. When the component force F1 becomes larger than a frictional force f1 in response to strength of the tensile force F, the lead wire 12 is likely to be removed from the pinch portion 22. The clearance 26b at the tip side of the pinch portion 22 may be made narrow in order to prevent removal of the lead wire 12. However, in this case, the insertion of the lead wire 12 is worsened.
The present invention is made in view of the above problem and it is an object to provide a sensor attachment structure in which a lead wire is prevented from being removed due to tensile force, without worsening insertion of the lead wire into a pinch portion.
In a sensor attachment structure according to the present invention, a lead wire connecting a sensor is pinched in a pinch portion provided at a tip side of an extending bar, at a position proximate to the sensor. The lead wire is extended along the extending bar and the extending bar is fixed to a fixing portion at the other side end. The pinch portion is constructed of a pair of wall plates protruding approximately perpendicular to an extending direction of the extending bar. Further, the pinch portion has a protrusion that protrudes toward the sensor in an extending direction of the extending bar. Further, the protrusion is provided with a contact surface that is inclined toward the sensor from the protruding direction of the pair of wall plates. When tensile force is exerted to the lead wire in an opposite direction to the sensor, the extending bar is deflected. According to the above structure, a component force along the contact surface toward the protruding direction can be reduced, and it can restrict the lead wire from being removed.
Preferably, when an inclination angle of the contact surface is equal to a deflection angle of the extending bar against the extending direction of the lead wire, the inclined direction of the contact surface becomes perpendicular to the tensile force. That is, a component force along the contact surface becomes zero. Therefore, the lead wire is accurately prevented from being removed from the pinch portion.
In the present invention, since the protrusion is provided at the tip end of the pinch portion toward the sensor, it is unnecessary to narrow the clearance defined in the pinch portion in order to prevent the removal of the lead wire. Accordingly, insertion of the lead wire into the pinch portion is not worsened.